Friday, May 20, 2016

In 2013 the CDC published a report listing the top 18drug-resistant threats to the United States. While CDIFF, CRE, and Neisseria gonorrhea were listed as the most urgent concerns, not far behind they listed a dozen 2nd tier threats, including multi-drug and Methicillin-Resistant Staphylococcus Aureus (MRSA).

Despite its significant morbidity and mortality, MRSA was relegated to a second tier threat primarily because there remain a few `last ditch' drugs (vancomycin, daptomycin, and linezolid) available to treat it, and because invasive MRSA infections in healthcare settings was seen as being as being on the decline in the U.S. in recent years.

The concern with MRSA, as with all drug resistant bacterial infections, is that it could eventually develop pan-resistance - where no effective treatment option remains.

This week the EID Journal carries a letter describing MRSA surveillance and testing at a single hospital in Odisha,
eastern India. Although the number of samples tested was small (n=47), they detected several samples displaying disturbing co-resistance to methicillin, vancomycin, linezolid, and
tigecycline.

First some excerpts from the letter, then I'll return with a bit more.

To the Editor: Methicillin-resistant Staphylococcus aureus (MRSA) is a versatile pathogen capable of causing a wide variety of human diseases. Increased frequency of S. aureus
infections imposes a high and increasing burden on healthcare
resources. In many countries, MRSA infections in hospitals are common.
Data from the National Nosocomial Infections Surveillance system suggest
that, in the United States, incidence of nosocomial MRSA infections is
steadily increasing and that these infections account for >60% of
intensive care unit admissions (1,2).

S. aureus
has developed resistance to several antimicrobial drugs, including
second- and third-line drugs. Only a few drugs, such as vancomycin (a
glycopeptide), daptomycin (a lipopeptide), and linezolid (an
oxazolidinone), have been approved for the treatment of serious
infections caused by MRSA. Another drug, tigecycline (a glycylcycline),
has shown good activity against MRSA strains in vitro (3).

The epidemiology of MRSA is constantly changing, which results in
variation in its drug-resistance patterns throughout regions and
countries (4).
Therefore, to support clinicians in preventing and treating infection,
epidemiologic surveillance is essential. We report resistance patterns
of S. aureus collected over 2 years (December 2013–November
2015) from blood samples of patients admitted to 1 hospital in Odisha,
eastern India.

(SNIP)

This study indicates the emergence of multidrug-resistant S. aureus
with co-resistance to methicillin, vancomycin, linezolid, and
tigecycline. Although the clinical significance of these findings is
unknown, the decline in drug effectiveness against S. aureus
infections represents a looming threat to patient health and highlights
the possibility of a return to illness and death rates similar to those
before antimicrobial drugs were available.

While the media loves to bombard us with apocalyptic warnings of global warming, asteroid strikes, and super volcanoes erupting, the slow motion disaster of growing antibiotic resistance is the one that is most likely to reach criticality my lifetime (and I'm a relatively old man).